Great topic/subject. For years it was good FM radio stations (meaning College ones, generally), as well as looking for connections on album liner notes. Brian Wilson lead me to Van Dyke Parks' Song Cycle, who lead me to Randy Newman's 1st, etc.
The great Americana print magazine No Depression exposed me to artists I had been unaware of (and continues to online), as did/does Mojo Magazine out of England. I also keep my ears open while browsing at record stores---employees at them are some of the most diehard music fans alive, and are very current. If you find one who shares your taste, he or she can let you know about the best new releases.